The present invention relates to a data transmitting device, a data receiving device, and a data recording device and, more particularly to an device which transmits, receives, or records output data of an MPEG (moving picture expert group) 2 encoder or data of an MPEG2 program stream recorded in a recording medium such as an optical disk, through a communication medium (interface) such an IEEE1394 system.
In recent years, attention has been focused on the IEEE1394 system as a serial transmission system for data.
The IEEE1394 system uses any of 100 Mbps, 200 Mbps, and 400 Mbps as a base rate of data transmission with a cycle time of 125 xcexcs (microsecond).
Also, the IEEE1394 system defines two communication methods, namely, an isochronous transfer (synchronous communication) and an asynchronous transfer. In the isochronous transfer, data is transmitted immediately in response to a transmission request, while in the asynchronous transfer, some delay may sometimes occur between generation of a transmission request and data transmission.
The isochronous transfer is a communication method for use by data transmission which must be made in real time, as is typical of transmission of AV (Audio Video) data. In the isochronous transfer, prior to the start of data transmission, a band required for data transmission is obtained. Then, with this band, data of at least one packet is transmitted once in one cycle (125 xcexcs), which ensures that data transmission is made in real time.
On the other hand, the asynchronous transfer is a communication method for use by data transmission which need not be made in real time, as in the case of transmission of computer data such as commands or still picture data. It is assumed that this is identical to a transmission system such as a conventional SCSI (small computer system interface).
Currently, for transmission of the AV data using the isochronous transfer, a method of transmitting data for digital VCR (Video Cassette Recorder), a method of transmitting MPEG2 transport stream data, and so forth are defined.
Now, a brief description is given of a communication method on a network N by the use of an interface according to the IEEE1394 (hereinafter referred to as 1394I/F).
FIG. 36(a) schematically shows a network to which three terminals are connected through the 1394I/F. Suppose that terminals A, B and C are a digital video camcoder (DVC), a personal computer for outputting the MPEG2 transport stream (TS) as image data, and a receiving device for image data, respectively. Also suppose that the terminal A is a main terminal for outputting cycle start packet per 125 xcexcs toward the network N, and allocating a frequency band for data transmission to each terminal.
In the 1384I/F, time for the isochronous transfer and time for asynchronous transfer are allocated for one cycle. Of the one cycle, 80% time period is used for the isochronous transfer, and the remaining 20% time period is used for the asynchronous transfer. Each terminal performs data transmission by the isochronous transfer for data which must be transmitted in real time, and performs data transmission by the asynchronous transfer for data which need not be transmitted in real time.
Initially, each of the terminals A-C declares a frequency band required for data transmission to the main terminal A, and requests permission for use of the band. If permitted, each terminal uses the band for data transmission, whereas if not permitted, it tries to request permission for use of reduced band. When the permission is granted, each terminal can transmit packet data by the isochronous transfer at least once in one cycle when it is necessary to perform the isochronous transfer.
Hereinafter, description is given of a case where the terminals A and B perform data transmission by the isochronous transfer, and the terminal C performs data transmission by the asynchronous transfer, with reference to FIG. 36(b).
Referring to FIG. 36(b), the main terminal A outputs cycle start packets St1, St2, St3, . . . , each indicating a head of each cycle in each cycle, and outputs isochronous packets Aiso1, Aiso2, Aiso3, . . . in each cycle.
The terminal B outputs isochronous packets Biso1, Biso2, Biso3, . . . , in each cycle.
The terminal C outputs an asynchronous packet Casyn1, subsequently to the isochronous packets Aiso1, and Biso1, in a cycle between the cycle start packets St1 and St2.
In a case where plural terminals output asynchronous packets, priority of the asynchronous packets is established among them in such a manner that priority decreases in the order in which transmission requests of the corresponding terminals are sent to the main terminal. In this case, asynchronous packets which have not been transmitted in one cycle will be transmitted in a subsequent cycle.
Meanwhile, in DVD (digital versatile disk)-Video standard, a method of recording compressively coded video data or audio data in a DVD disk as a recording medium is defined.
Assume that compressively coded video data or audio data is read from the recording medium such as the DVD, and AV decoding is performed thereto. In this case, in general, data is read from the recording medium at a rotation rate higher than a rotation rate corresponding to normal data processing rate, and data is read intermittently.
As shown in FIG. 37, a reproducing device 10 such as a DVD player, includes a buffer 12 at a previous stage of an AV data decoder 13, for storing read data therein to buffer difference between a data readout rate and a data processing rate. In FIG. 37, reference numeral 11 designates an optical head for reading data from the DVD disk1, and reference numeral 14 designates a display such as TV (Television Set) which displays image data or outputs audio data on the basis of an output of the AV data decoder 13.
In the DVD player thus constructed, data transfer from the recording medium 1 to the buffer 12 is controlled according to amount of data stored in the buffer 12. In response to a request Re from the AV data decoder 13, data Da is then transferred from the buffer 12 to the AV data decoder 13.
Here, assume that a digital interface (I/F) 15 is added to the DVD player as shown in FIG. 38.
At a transmitting end, a transmitting device 10 transfers data from the recording medium 10a to the buffer 12, and then outputs data to the digital interface 15.
Meanwhile, at a receiving end, a receiving device 20 receives data through a digital interface 21, and then an AV data decoder 22 decodes received data and outputs decoded data to the TV or the like.
In this case, since data is output from the buffer 12 in response to a request Rq2 from the AV data decoder 22 of the receiving device 20, the request Rq2 must be transmitted through the digital interfaces 21 and 15 at the receiving end and the transmitting end, respectively.
Besides, in another case where plural devices receives data, since operations of the corresponding AV data decoders might differ from each other, it is required that a transmitting device at the transmitting end output data in response to requests from respective receiving devices at the receiving end. Therefore, a transmitting device at the transmitting end must read data from a recording medium at a very high rate.
Data recorded in the DVD is data which takes an MPEG2 program stream format (hereinafter referred to as MEPEG2-PS data). In order to transmit the MEPEG2-PS data through the 1394I/F as the digital interface 15 in FIG. 38(a), that is, to transmit it according to a transmitting method of the conventional MPEG2 transport stream format data (hereinafter referred to as MPEG2-TS data), it is required that the MEPEG2-PS data be converted into the MPEG2-TS data.
Hereinbelow, description is given of problems associated with transmission of the MEPEG2-PS data recorded in the DVD through the 13941/F from the transmitting end to the receiving end with reference to FIG. 39.
FIG. 39 shows detailed structures of the interfaces 15 and 21 of transmitting device 10a and receiving device 20a in FIG. 38, respectively. The interface 15 of the transmitting device 10 comprises a conversion unit 15a for converting the MEPEG2-PS data output from the buffer 12 into the MPEG2-TS data, and a transmitting end 1394I/F 15b connected to an output area of the conversion unit 15a. The interface 21 comprises a receiving end 1394I/F 21a for receiving the MPEG2-TS data from the transmitting end over an network N, and a conversion unit 21b for converting the MPEG2-TS data from the 1394I/F 21a into the MPEG2-PS data.
In order to transmit the MEPEG2-PS data recorded in the DVD through the 1394I/F, it is required that the MPEG2-PS data be converted into the MPEG2-TS data on the transmitting end, and the MPEG2-TS data be converted into the MEPEG2-PS data at the receiving end.
However, there have been many problems associated with the above data conversion, which will be described below.
i) The MEPEG2-PS data and the MPEG2-TS data have contents of data description which differ from each other in their respective headers, and therefore information of the headers must be changed, causing complicated data processing.
ii) The MEPG2-PS data and the MPEG2-TS data respectively contain clock reference (time data) which a decoder use. The clock reference of the MEPEG2-PS data is called xe2x80x9cSCRxe2x80x9d (System Clock Reference), and the clock reference of the MPEG2-TS data is called xe2x80x9cPCRxe2x80x9d (Program Clock Reference). According to MPEG2, the largest interval of the SCR is 700 ms, and the largest interval of the PCR is 100 ms. When converting the MEPEG2-PS data into the MPEG2-TS data, more clock references must be created, and therefore there is a need for a circuit for generating a high-precision timing signal at a transmitting end.
The MEPEG2-PS data recorded in the DVD contains data unique to the DVD (Navigation data or the like) in a private stream format. When the MPEG2-TS data into which the MEPEG2-PS data has been converted is decoded by a decoder for TS, the data unique to the DVD cannot be decoded. For this reason, it is necessary that the MPEG2-TS data output from the 1395I/F 21a be inversely converted into the MEPEG2-TS data at the receiving end, causing a complicated structure of receiving device.
Assuming that transmitting device is a DVD recorder 10b for performing coding to a TV signal and recording a coded TV signal in a recording medium 1 such as the DVD, as in the case of the DVD recorder 10, what is needed is that the DVD recorder 10b includes a conversion unit 17 for converting the MEPEG2-TS data output from an MPEG2 program stream encoder (elementary and system) 16 into the MPEG2-TS data, and an output of the conversion unit 17 is signal is sent onto an network N through an 1394I/F unit 18.
The recording medium such as the optical disc contains data which has been subjected to error correction coding and modulation. In a case where the data us read from the recording medium such as the optical disk, it track jump may fails and the same data is reread therefrom, a buffer may underflow, or if ECC (error correction code) decoding may develop an error, and the same data is reread therefrom, a buffer may underflow in the system in FIG. 38.
In this case, even if the AV data decoder 13 at a transmitting end issues a data request to the buffer, data will not be output therefrom, or it is not correct data if output. The same goes for data output to the digital interface 15. Hence, in the system shown in FIG. 38, the AV data decoder 22 at the receiving end cannot perform correct decoding, causing an incorrect video or audio signal to be reproduced. In other words, in the system shown in FIG. 38, when reading data from a recording medium such as an optical disk has developed an error in the transmitting device, if read data is transmitted to the receiving end through the digital interface, the data cannot be AV decoded correctly at the receiving end.
It is an object of the present invention to provide a data transmitting device which can transmit MPEG2 program stream data output from an MPEG2 encoder (elementary and system) or recorded in a recording medium by the use of an 1394I/F without the necessity of converting it into an MPEG2 transport stream.
It is another object of the present invention to provide a data receiving device which can receive the MPEG2 program stream data transmitted by the use of the 1394I/F and can decode the same correctly, and a data recording device which can record the MPEG2 program stream data transmitted by the use of the 13941I/F in a prescribed recording format.
It is still another object of the present invention to provide a data transmitting device which can transmit data which will be decoded correctly at a receiving end, and a data receiving device which can correctly decode the data transmitted from the data transmitting device, even if underflow or an ECC error occurs in a buffer at a transmitting end while data recorded in a recording medium is transmitted.
Other objects and advantages of the present invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the spirit and scope of the invention will be apparent to those skill in the art from the detailed description.
According to first aspect of the present invention, a data transmitting device connected to a prescribed network, comprises coding means for receiving plural kinds of coded data, and coupling these coded data in first data units to generate a first coded stream; dividing means for dividing the first coded stream in second data units of a prescribed data size to generate divided pack data corresponding to divided packs as the second units; packet generating means for adding header information to respective divided pack data to generate packet data corresponding to packets as data transmission units; and transmitting means for outputting the respective packet data toward the network as a second coded stream which has a data structure different from that of the first coded stream. Therefore, the MPEG2 program stream data or the like cane divided into packets which are smaller than its data units. As a result, the MPEG2 program stream or the like cane output toward the network by a transmitting method of the transport stream, that is, through the IEEE 1394I/F, without the necessity of converting it into the MPEG transport stream.
In addition, in a receiving device at a receiving end connected to the network, received data packets are coupled, thereby restoring the MPEG2 program stream generated by the data transmitting device.
According to a second aspect of the present invention, in the data transmitting device as defined in the first aspect, the dividing means divides the first coded stream in such a manner that the divided packs each contains coded data of one kind. Therefore, the MPEG2 program stream can be restored easily at the receiving end.
According to a third aspect of the present invention, in the data transmitting device as defined in the second aspect, the packet generating means generates packet data by adding stuffing data to a divided pack of a size smaller than the prescribed data size so that all the generated packets are of the same size. Therefore, packet data is easy to handle at the transmitting end and the receiving end.
According to a fourth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises reading means for reading data recorded in sector units of a prescribed data size in a recording medium for each sector; dividing means for dividing data corresponding to each sector read by the reading means in data units of a data size smaller than that of the sector, to generate divided pack data corresponding to divided packs as the data units; packet generating means for adding header information to respective divided pack data, to generate packet data corresponding to packets as data transmission units; and transmitting means for outputting respective packet data toward the network. Therefore, the MPEG2 program stream or the like can be output toward the network by a transmitting method of the transport stream, that is, through the IEEE 1394I/F, without the necessity of converting it into the MPEG transport stream.
According to a fifth aspect of the present invention, in the data transmitting device as defined in the fourth aspect, the dividing means divides the data corresponding to the sector so that head data of each sector matches head data of the corresponding divided pack. Therefore, packet data is easy to handle at the receiving end.
According to a sixth aspect of the present invention, in the data transmitting device as defined in the fourth or fifth aspect, the packet generating means generates packet data by adding information indicating that a divided pack contains head data of the corresponding sector to the divided pack. Therefore, divided packs can be restored to a pack with ease at a receiving end. Besides, the pack is divided in arbitrary byte units, thereby realizing effective use of a band of a digital interface such as the 1394I/F.
According to a seventh aspect of the present invention, a data receiving device for receiving packet data output from the data transmitting device as defined in any of the fourth to sixth aspects as a coded stream, comprises receiving means for receiving the packet data and outputting the divided pack data corresponding to each packet according to analysis of its header information; and coupling means for coupling the divided pack data output from the receiving means to generate data corresponding to the sector. Therefore, based on packet data output from the data transmitting device, the MPEG2 program stream or the like generated by the data transmitting device can be correctly restored.
According to an eighth aspect of the present invention, a data recording device for receiving and recording packet data output as a coded stream from the data transmitting device as defined in any of the fourth to sixth aspects, comprises receiving means for receiving the packet data and outputting the divided pack data corresponding to each packet according to analysis of its header information; coupling means for coupling the divided pack data output from the receiving means to generate data corresponding to the sector; and recording means for recording the data corresponding to the sector output from the coupling means in a recording medium having a sector structure. Therefore, based on packet data output from the data transmitting device, the MPEG2 program stream or the like generated by the data transmitting device can be correctly restored and recorded.
According to a ninth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium; buffer means for temporarily storing the data read by the data reading means; and data transmitting means for outputting the data output from the buffer means, toward the network; wherein, when the buffer means goes into underflow state, the data transmitting means outputs underflow information indicating that underflow has occurred in the buffer means, toward the network. Therefore, even when underflow has occurred in a buffer at the transmitting end, the receiving end detects the occurrence of underflow and converts the operating mode from the normal mode to the error handling mode. As the result, speedy error-handling is realized at the receiving end, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to a tenth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium; buffer means for temporarily storing the data read by the data reading means; packet generating means for adding header information to the data output from the buffer means, and generating packet data corresponding to a packet which is a unit of data transmission; and data transmitting means for outputting the packet data output from the packet generating means, toward the network; wherein, when the buffer means goes into underflow state, the packet generating means adds underflow information to a header section of the packet, which information indicates that underflow has occurred in the buffer means, and outputs the packet toward the data transmitting means. Therefore, even when underflow has occurred in a buffer at the transmitting end, the receiving end detects the occurrence of underflow and performs speedy error-handling, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to an eleventh aspect of the present invention, in the data transmitting device of the tenth aspect, the data transmitting means repeats, at fixed time intervals, packet-by-packet data transmission for outputting at least one packet data to the network at a fixed transmission rate; and the packet generating means adds the underflow information to a header of an isochronous packet used in isochronous transfer in which the data transmission is performed synchronously with a transfer request generated by the data transmitting means.
According to a twelfth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium; buffer means for temporarily storing the data read by the data reading means; and data transmitting means for outputting the data output from the buffer means, toward the network; wherein, when the buffer means goes into underflow state, the data transmitting means output data of a prescribed pattern to the network, as underflow information indicating that underflow has occurred in the buffer means. Therefore, even when underflow has occurred in a buffer at the transmitting end, the receiving end detects the occurrence of underflow and performs speedy error-handling, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to a thirteenth aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving data output from the data transmitting device of the ninth aspect; data analyzing means for analyzing the data received by the data receiving means, and outputting information indicating that underflow has occurred at the transmitting end when underflow information is included in the data; and data decoding means for performing decoding based on the data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of underflow. Therefore, the receiving end detects that underflow has occurred in a buffer at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to a fourteenth aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving packet data output from the data transmitting device of the tenth aspect; data analyzing means for analyzing the packet data received by the data receiving means, and outputting information indicating that underflow has occurred at the transmitting end when underflow information is included in the packet data; and data decoding means for performing decoding based on the packet data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of underflow. Therefore, the receiving end detects that underflow has occurred in a buffer at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to a fifteenth aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving isochronous packet data output from the data transmitting device of the eleventh aspect; data analyzing means for analyzing the isochronous packet data received by the data receiving means, and outputting information indicating that underflow has occurred at the transmitting end when the underflow information is included in the header of the isochronous packet data; and data decoding means for performing decoding based on the isochronous packet data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of underflow. Therefore, the receiving end detects the underflow has occurred in a buffer at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to sixteenth aspect of the present invention, a data receiving device connected to a prescribe network, comprises data receiving means for receiving data output from the data transmitting device of the twelfth aspect; data analyzing means for analyzing the data received by the data receiving means, and outputting information indicating that underflow has occurred at the transmitting end when the data of a prescribed pattern is included in the received data; and data decoding means for performing decoding based on the data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of underflow. Therefore, the receiving end detects that underflow has occurred in a buffer at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the occurrence of underflow in the buffer at the transmitting end can be suppressed effectively.
According to a seventeenth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium, which data is given an error-correcting code; error detecting means for detecting whether an error exists in data processing or not, by decoding the error-correcting code included in the data read by the data reading means; and data tram sitting means for outputting the data read from the data reading means toward the network; wherein, when an error in data processing is detected by the error detecting means, the data transmitting means outputs error information indicating the occurrence of error in data processing, toward the network. Therefore, even when an ECC error has occurred during ECC decoding of data read from the recording media, the receiving end detects the occurrence of the ECC error, and converts the operating mode from the normal mode to the error handling mode. As a result, speedy error-handling is realized at the receiving end, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to an eighteenth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium, which data is given an error-correcting code; error detecting means for detecting whether an error exists in data processing or not, by decoding the error-correcting code included in the data read by the data reading means; packet generating means for adding header information to the data read by the data reading means, and generating packet data corresponding to a packet which is a unit of data transmission; and data transmitting means for transmitting the packet data output from the packet generating means, toward the network; wherein, when an error in data processing is detected by the error detecting means, the packet generating means adds error information to a header section of the packet, which information indicates that an error has occurred in data processing, and outputs the packet toward the data transmitting means. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a nineteenth aspect of the present invention, in the data transmitting device of the eighteenth aspect, the data transmitting means repeats, at fixed time intervals, packet-by-packet data transmission for outputting at least one packet data to the network at a fixed transmission rate; and the packet generating means adds the error information to a header of an isochronous packet used in isochronous transfer in which the data transmission is performed synchronously with a transfer request generated by the data transmitting means.
According to a twentieth aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium, which data is given an error-correcting code; error detecting means for detecting whether an error exists in data processing or not, by decoding the error-correcting code included in the data read by the data reading means; and data transmitting means for transmitting the data read by the data reading means toward the network; wherein, when an error in data processing is detected by the error detecting means, the data transmitting means outputs data of a prescribed pattern to the network, as information indicating that an error has occurred in data processing. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-first aspect of the present invention, a data transmitting device connected to a prescribed network, comprises data reading means for reading data recorded in a recording medium, which data is given an error-correcting code; error detecting means for detecting whether an error exists in data processing or not, by decoding the error-correcting code included in the data read by the data reading means; packet generating means for adding header information to the data read by the data reading means, and generating packet data corresponding to a packet which is a unit of data transmission; and data transmitting means for transmitting the packet data output from the packet generating means toward the network; wherein, when an error in data processing is detected by the error detecting means, the packet generating means adds incorrect cyclic redundancy check data to the packet data, as information indicating that an error has occurred in data processing, and outputs the packet data. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-second aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving data output from the data transmitting device of the seventeenth aspect; data analyzing means for analyzing the data receiving by the data receiving means, and outputting information indicating that an error has occurred in data processing at the transmitting end when the error information is included in the received data; and data decoding means for performing decoding based on the data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of error in data processing. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-third aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving packet data output from the data transmitting device of the eighteenth aspect; data analyzing means for analyzing the packet data received by the data receiving means, and outputting information indicating that an error has occurred in data processing at the transmitting end when the error information is included in the packet data; and data decoding means for performing decoding based on the packet data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of error in data processing. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-fourth aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving isochronous packet data output from the data transmitting device of the nineteenth aspect; data analyzing means for analyzing the isochronous packet data received by the data receiving means, and outputting information indicating that an error has occurred in data processing at the transmitting end when the error information is included in the header of the isochronous packet data; and data decoding means for performing decoding based on the isochronous packet data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of error in data processing. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-fifth aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving data output from the data transmitting device of the twentieth aspect; data analyzing means for analyzing the data received by the data receiving means, and outputting information indicating that an error has occurred in data processing at the transmitting end when the data of a prescribed pattern is included in the received data; and data decoding means for performing decoding based on the data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating the occurrence of error in data processing. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-sixth aspect of the present invention, a data receiving device connected to a prescribed network, comprises data receiving means for receiving packet data output from the data transmitting device of the twenty-first aspect; data analyzing means for analyzing the packet data received by the data receiving means, and outputting information indicating that the cyclic redundancy check data is incorrect, when the cyclic redundancy check data included in the header section of the packet data is incorrect; and data decoding means for performing decoding based on he packet data received by the data receiving means, and converting the operating mode of the decoding from normal mode to error handling mode on receipt of the information indicating that the cyclic redundancy check data is incorrect. Therefore, the receiving end detects that an error in data processing, such as an ECC error, has occurred at the transmitting end, and performs speedy error-handling, whereby disorder of video and audio signals due to the ECC error can be suppressed effectively.
According to a twenty-seventh aspect of the present invention, the data transmitting device as defined in any of the ninth and twelfth aspects, comprises dividing means for dividing data output from the buffer means in data units of a data prescribed size, to generate divided pack data corresponding to divided packets as the data units; and packet generating means for adding header information to respective divided pack data to generate packet data corresponding to packets as data transmission units, the data transmitting means outputting the packet data toward the network as data output from the buffer means. If underflow may occur in the buffer at the transmitting end, this is detected, and error is processed speedily at the receiving end, whereby disorder of the video or audio signal due to occurrence of underflow can be effectively suppressed. Besides, the MPEG2 program stream data recorded in sector units in a recording medium such as DVD can be divided into packets smaller than the sector. As a result, the MPEG2 program stream or the like can be output toward the network by a transmitting method of the transport stream, that is, through the IEEE 1394I/F, without the necessity of converting it into the MPEG transport stream.
According to a twenty-eighth aspect of the present invention, a data receiving device connected to a prescribed network, comprises receiving means for receiving packet data output from the data transmitting device of the twenty seventh aspect; data analyzing means for analyzing the packet data received by the data receiving means, and outputting information indicating that underflow has occurred at a transmitting end when the packet data contains the underflow information; and data decoding means for performing decoding based on the packet data received by the data receiving means, and converting decoding operating mode from normal mode to error handling mode, upon receipt of the information indicating that underflow has occurred. Therefore, the underflow is detected at the receiving end, and error is processed speedily, whereby disorder of the video or audio signal due to occurrence of underflow can be effectively suppressed. Besides, based on packet data output from the data transmitting device, the MPEG2 program stream or the like generated by the data transmitting device can be restored.
According to a twenty-ninth aspect of the present invention, in the data transmitting device as defined in any of tenth or eleventh aspect further comprises: dividing means for dividing data output from the buffer means in data units of a prescribed data size, to generate divided pack data corresponding to divided packs as the data units, the packet generating means receiving the divided pack data as the data output from the buffer means and adding header information to respective divided pack data to generate the packet data. Besides, the MPEG2 program stream data recorded in sector units in a recording medium such as DVD can be divided into packets smaller than the sector. As a result, the MPEG2 program stream or the like can be output toward the network by a transmitting method of the transport stream, that is, through the IEEE 1394I/F, without the necessity of converting it into the MPEG transport stream.
According to a thirty aspect of the present invention, in a data receiving device connected to a prescribed network, comprises receiving means for receiving packet data output from the data transmitting device of the twenty ninth aspect, data analyzing means for analyzing the packet data received by the data receiving means, and outputting information indicating that underflow has occurred at a transmitting end when the packet data contains the underflow information; and data decoding means for performing decoding based on the packet data received by the data receiving means, and converting decoding operation mode from normal mode to error handling mode, upon receive of the information indicating that underflow has occurred. Therefore, the underflow is detected at the receiving end, and error is processed speedily, whereby disorder of the video or audio signal due to occurrence of underflow can be effectively suppressed. Besides, based on the received packet data, the MPEG2 program stream data generated at the transmitting end or the like can be restored.
According to a thirty-first aspect of the present invention, in the data transmitting device as defined in any of seventeenth and twentieth aspects, further comprises dividing means for dividing data read from the data reading means in data units of a prescribed data size, to generate divided pack data corresponding to divided packs as the data units; and packet generating means for adding header information to respective divided pack data to generate packet data corresponding to packets as data transmission units, the data transmitting means outputting the packet data toward the network as the data read by the data reading means. Therefore, if an ECC error may occur when performing ECC decoding to data read from the recording medium, this is detected, and the operating mode switched from normal mode to error handling mode, whereby error is processed speedily, and disorder of the video or audio signal due to occurrence of underflow can be effectively suppressed. Besides, the MPEG2 program stream data recorded in sector units in a recording medium such as DVD can be divided into packets smaller than the sector. As a result, the MPEG2 program stream or the like can be output toward the network by a transmitting method of the transport stream, that is, through the IEEE 1394I/F, without the necessity of converting it into the MPEG transport stream.
According to a thirty-second aspect of the present invention, a data receiving device connected to a prescribed network, comprises receiving means for receiving packet data output from the data transmitting device of the thirty first; data analyzing means for analyzing packet data received by the data receiving means and outputting information indicating that an error has occurred in data processing at a transmitting end when the packet data contains the error information; and data decoding means for performing decoding based on the packet data received by the data receiving means, and converting decoding operation mode from normal mode to error handling mode, upon receipt of the information indicating that the error has occurred in the data processing. Therefore, ECC error at the transmitting end is detected, and disorder of video or audio signal due to the error can be effectively suppressed at the receiving end. Besides, based on the received packet data, the MPEG2 program stream data generated at the transmitting end or the like can be restored.
According to a thirty-third aspect of the present invention, in the data transmitting device as defined in any of the eighteenth, nineteenth, and twenty first aspects further comprises dividing means for dividing data read by the data reading means in data units of a prescribed data size, to generate divided pack data corresponding to divided packs as the data units, the packet generating means receiving the divided pack data as the data read by the data reading means and adding header information to respective divided pack data to generate the packet data. If an ECC error may occur when performing ECC decoding to data read from the recording medium, this is detected, and the operating mode switches from normal mode to error handling mode, whereby error is processed speedily, and disorder of the video or audio signal due to occurrence of underflow can be effectively suppressed. Besides, the MPEG2 program stream data recorded in sector units in a recording medium such as DVD can be divided into packets smaller than the sector. As a result, the MPEG2 program stream or the like can be output toward the network by a transmitting method of the transport stream, that is, through the IEEE 1394I/F, without the necessity of converting it into the MPEG transport stream.
According to a thirty-fourth aspect of the present invention, a data receiving device connected to a prescribed network, comprises receiving means for receiving packet data output from the data transmitting device of the thirty third aspect; data analyzing means for analyzing the packet data received by the data receiving means, and outputting information indicating that an error has occurred in data processing at a transmitting end when the packet data contains the error information; and data decoding means for performing decoding based on the packet data received by the data receiving means, and converting decoding operation mode from normal mode to error handling mode, upon receipt of the information indicating that the error has occurred in the data processing. Therefore, ECC error at the transmitting end is detected, and disorder of video or audio signal due to the error can be effectively suppressed at the receiving end. Besides, based on the received packet data, the MPEG2 program stream data generated at the transmitting end or the like can be restored.